Citizendia
Your Ad Here

286
Central processing unit

An Intel 80286 Microprocessor
Produced: From 1982 to early 1990s
Common manufacturers:
Max CPU clock: 6 MHz to 25 MHz
Min feature size: 1. Harris Corporation ( is an international communications equipment company that produces Wireless equipment electronic systems and both terrestrial and spaceborne antennas The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. 5 µm
Instruction set: x86-16 (with MMU)
Package: PLCC 68-pin
AMD 80286 at 12 MHz.
AMD 80286 at 12 MHz. A micrometre ( American spelling: micrometer; symbol µm) is one millionth of a Metre, or equivalently one thousandth of a Millimetre An instruction set is a list of all the instructions and all their variations that a processor can execute See also X86 assembly language The generic term x86 refers to the most commercially successful Instruction set architecture in the history of Personal A memory management unit ( MMU) sometimes called paged memory management unit ( PMMU) is a Computer hardware component responsible for handling A Plastic Leaded Chip Carrier (PLCC is a four-sided “J”-leaded plastic Integrated circuit package with pin spacings of 0
Harris 80286 at 16 MHz.
Harris 80286 at 16 MHz.
Siemens 80286 at 10 MHz.
Siemens 80286 at 10 MHz.

The Intel's 286[1], introduced on February 1, 1982, (originally named 80286, and also called iAPX 286 in the programmer's manual) was an x86 16-bit microprocessor with 134,000 transistors. Events 1327 - Teenaged Edward III is crowned King of England, but the country is ruled by his mother Queen Year 1982 ( MCMLXXXII) was a Common year starting on Friday (link displays the 1982 Gregorian calendar) See also X86 assembly language The generic term x86 refers to the most commercially successful Instruction set architecture in the history of Personal A microprocessor incorporates most or all of the functions of a Central processing unit (CPU on a single Integrated

It was widely used in IBM PC compatible computers during the mid 1980s to early 1990s. IBM PC compatible computers are those generally similar to the original IBM PC, XT, and AT. A computer is a Machine that manipulates data according to a list of instructions.

After the 6 and 8 MHz initial releases, it was subsequently scaled up to 12. The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. 5 MHz. (AMD and Harris later pushed the architecture to speeds as high as 20 MHz and 25 MHz, respectively. Harris Corporation ( is an international communications equipment company that produces Wireless equipment electronic systems and both terrestrial and spaceborne antennas ) On average, the 80286 had a speed of about 0. 21 instructions per clock. In Computer architecture, Instructions Per Clock ( Instruction Per Cycle or IPC) is a term used to describe one aspect of a processor 's performance [2] The 6 MHz model operated at 0. 9 MIPS, the 10 MHz model at 1. 5 MIPS, and the 12 MHz model at 2. 66 MIPs. [3]

The 80286's performance was more than twice that of its predecessors (the Intel 8086 and Intel 8088) per clock cycle. The 8086 is a 16-bit Microprocessor chip designed by Intel and introduced on the market in 1978 which gave rise to the X86 architecture The Intel 8088 is an Intel X86 Microprocessor based on the 8086, with 16- Bit registers and an 8-bit external Data bus In Electronics and especially synchronous Digital circuits a clock signal is a signal used to coordinate the actions of two or more circuits In fact, the performance increase per clock cycle of the 80286 over its immediate predecessor may be the largest among the generations of x86 processors. Calculation of the more complex addressing modes (such as base+index) had less clock penalty because it was performed by a special circuit in the 286; the 8086, its predecessor, had to perform effective address calculation in the general ALU, taking many cycles. Addressing modes are an aspect of the Instruction set architecture in most Central processing unit (CPU designs Addressing modes are an aspect of the Instruction set architecture in most Central processing unit (CPU designs In Computing, an arithmetic logic unit ( ALU) is a Digital circuit that performs Arithmetic and Logical operations Also, complex mathematical operations (such as MUL/DIV) took fewer clock cycles compared to the 8086.

Having a 24-bit address bus, The 286 was able to address up to 16 MB of RAM, in contrast to 1 MB that the 8086 could directly work with. A mebibyte (a contraction of me ga bi nary byte) is a unit of Information or Computer storage, abbreviated MiB. While DOS could utilize this additional RAM (extended memory) via BIOS call (INT 15h, AH=87h), or as RAM disk, or emulation of expanded memory, cost and initial rarity of software utilizing extended memory meant that 286 computers were rarely equipped with more than a megabyte of RAM. DOS, short for "Disk Operating System" is a shorthand term for several closely related Operating systems that dominated the IBM PC compatible market In computing Extended memory refers to memory above the first Megabyte of Address space in an IBM PC with an 80286 or later In Computing, the BIOS (ˈbaɪoʊs A RAM disk is a software layer that enables applications to transparently use RAM, often a segment of Main memory, as if it was a Hard disk An emulator duplicates (provides an emulation of the functions of one System using a different system so that the second system behaves like (and appears to In computing expanded memory (commonly known as EMS memory) is a system of Bank switching introduced around 1984 that provided additional memory to MS-DOS

The 286 was designed to run multitasking applications, including communications (such as automated PBXs), real-time process control, and multi-user systems. In Computer science, real-time computing (RTC is the study of hardware and software systems that are subject to a "real-time constraint"—i Process control is a Statistics and Engineering discipline that deals with Architectures mechanisms and Algorithms for controlling Multi-user is a term that defines an Operating system or Application software that allows concurrent access by multiple users of a Computer.

The later E-stepping level of the 80286 was a very clean CPU - free of the several significant errata that caused problems for programmers and operating system writers in the earlier B-step and C-step CPU's (common in the AT and AT clones).

An interesting feature of this processor is that it was the first x86 processor with protected mode. In computing protected mode, also called protected virtual address mode, is an operational mode of X86 -compatible Central processing units (CPU Protected mode enabled up to 16 MiB of memory to be addressed by the on-chip linear memory management unit (MMU) with 1 GiB logical address space. A memory management unit ( MMU) sometimes called paged memory management unit ( PMMU) is a Computer hardware component responsible for handling In Data Networks In computer networks a logical address refers to a Network layer address such as an IP 192 The MMU also provided some degree of prevention from (crashed or ill-behaved) applications writing outside their allocated memory zones. However, the 286 could not revert to the basic 8086-compatible "real mode" without resetting the processor (though some very clever programmers did figure out a way to re-enter real mode via a series of software instructions which would execute the reset while retaining active memory and control). Real mode, also called real address mode, is an operating mode of 80286 and later X86 -compatible CPUs. The Intel 8042 keyboard controller at IBM PC/AT had a function to initiate a "soft boot" which resets a host CPU only. The Intel 8048 Microcontroller (µC (MCS-48 Intel's first microcontroller was used in the Magnavox Odyssey² Video game console, the Roland Jupiter-4 The IBM Personal Computer/AT, more commonly known as the IBM AT and also sometimes called the PC AT or PC/AT, was IBM 's second-generation

This limitation led to Bill Gates famously referring to the 80286 as a 'brain dead chip'[4], since it was clear that the new Microsoft Windows environment would not be able to run multiple MS-DOS applications with the 286. If you would like to experiment with Wikipedia please copy Microsoft Windows is a series of Software Operating systems and Graphical user interfaces produced by Microsoft. MS-DOS (short for M icro' s' oft D isk O perating S ystem is an Operating system commercialized by Microsoft. It was arguably also responsible for the split between Microsoft and IBM, since IBM insisted that OS/2, originally a joint venture between IBM and Microsoft, would run on a 286 (and in text mode). Microsoft Corporation is an American multinational Computer technology Corporation, which rose to dominate the Home computer International Business Machines Corporation abbreviated IBM and nicknamed "Big Blue", is a multinational Computer Technology OS/2 is a computer Operating system, initially created by Microsoft and IBM, then later developed by IBM exclusively

In theory, real mode applications could be directly executed in 16-bit protected mode if certain rules were followed; however, as many DOS programs broke those rules protected mode was not widely used until the appearance of its successor, the 32-bit Intel 80386, which was designed to go back and forth between modes easily. The range of Integer values that can be stored in 32 bits is 0 through 4294967295 or −2147483648 through 2147483647 using Two's complement encoding See Protected mode#Real mode application compatibility for more info. In computing protected mode, also called protected virtual address mode, is an operational mode of X86 -compatible Central processing units (CPU

The 80286 provided the first glimpse into the world of the protection mechanisms then exclusive to the world of mainframes and minicomputers which would pave the way for the x86 and the IBM PC architecture to extend from the personal computer all the way to high-end servers, drive the market for other architectures all the way down to only the highest-end servers and mainframes, and blur the differences between microcomputers and mainframes, a fact which presumably gave the IBM PC/AT its name. The IBM Personal Computer/AT, more commonly known as the IBM AT and also sometimes called the PC AT or PC/AT, was IBM 's second-generation

See also

Notes and references

  1. ^ Microprocessor Hall of Fame. LOADALL is the common name for two different undocumented machine instructions of Intel 80286 and Intel 80386 processors which allow access to areas normally outside Intel. Retrieved on 2007-08-11. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 2492 BC - Traditional date of the defeat of Bel by Hayk, progenitor and founder of the Armenian nation
  2. ^ Intel Architecure Programming and Information
  3. ^ http://content.cdlib.org/ark:/13030/kt7h4nc9c2/?layout=metadata&brand=calisphere
  4. ^ Microprocessors: A Programmer's View, Robert B. K. Dewar and Matthew Smosna, New York: McGraw-Hill, 1990, ISBN:0-07-016638-2

External links

© 2009 citizendia.org; parts available under the terms of GNU Free Documentation License, from http://en.wikipedia.org
 Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic